Synthesis of higher polyol fatty acid polyesters by transesterification

Abstract

A process for synthesizing polyol fatty acid polyesters comprising the steps of (1) mixing ingredients comprising (a) unesterified first polyol having hydroxyl groups, (b) second polyol esterified with fatty acids, (c) basic catalyst, and (d) emulsifying agent to form a mixture of ingredients; (2) reacting the mixture of ingredients at a temperature sufficient to obtain a transesterification reaction products and by-products; and (3) removing at least a portion of the by-products from the transesterification reaction mixture; and (4) further heating the transesterification reaction products and ingredients from step (3) at a temperature and for a time sufficient to esterify at least about 50% of the hydroxyl groups of the first polyol.

Description

This invention relates to processes for the production of polyol fatty acid polyesters, which processes eliminate the need to synthesize and purify lower alkyl ester intermediates. More particularly, this invention relates to processes for synthesizing polyol fatty acid higher polyesters by reaction of unesterified polyol, preferably selected from the group consisting of monosaccharides, disaccharides, polysaccharides, sugar alcohols, sugar ethers, polyglycerols and polyalkoxylated glycerols, and a second polyol esterified with fatty acids and selected from monoglycerides, diglycerides and triglycerides.The food industry has recently focused attention on polyol polyesters for use as low-calorie fats in food products. Triglycerides (triacylglycerols) constitute about 90% of the total fat consumed in the average diet. One method by which the caloric value of edible fat can be lowered is to decrease the amount of triglycerides that is consumed, since the usual edible triglyceride fats ...

AI Technical Summary

Benefits of technology

It is an additional object of this invention to provide novel processes for the production of polyol fatty acid polyesters which eliminate the need to ship, handle, capture, and / or recycle lower alkyl alcohol.

It is also an object of this invention to provide novel processes for the production of polyol fatty acid polyesters which eliminate discharge of lower alkyl alcohol to the environment.

It is yet another object of this invention to provide such processes which provide higher yields and which reduce undesirable color formation.

It has now been found that higher sucrose polyesters can be produced without the use of lower alkyl ester intermediates or methyl carbitol by transesterification of sucrose by triglyceride. Glycerine, mono- and / or di-glycerides, the by-products of the reaction, are derived from the triglyceride when at least one ester group of the triglyceride has been transferred to sucrose. Removal of glycerine, mono- and / or di-glycerides drives the reaction to high degrees of esterification, and polyol penta-to octa-esters are formed. The need to produce fatty acid lower alkyl esters in a separate step and the need to separate lower alkyl alcohol are eliminated by these processes, resulting in more economic processes. Eliminating the production of lower alkyl alcohol also eliminates the risk of the alcohol being released into the environment

It has also surprisingly been found that sucrose polyesters can be produced in a three-step process without using basic transesterification catalysts in the second step. Eliminating the basic transesterification catalyst from the second step provides higher yields and reduces undesirable color formation. A decrease in color formation increases the ease of product purification.

Problems solved by technology

Unfortunately, the need to synthesize fatty acid lower alkyl ester intermediates increases the operating costs of the polyol polyester synthetic process, and the reaction of polyol and fatty acid lower alkyl ester results in the production of lower alkyl alcohol as a by-product.

Systems for the capture of lower alkyl alcohol are required, and the need to separate and handle the lower alkyl alcohol increases the risk of discharges of alcohol into the environment.

Unfortunately, methyl carbitol is relatively toxic and would be unsuitable for use in food grade polyol polyester production.

Parker et al., U.S. Pat. No. 3,996,206, teach that sucrose mono-and di-esters are valuable surfactants, while the sucrose octa-esters are unsatisfactory surfactants.

Gallymore et al. teach that sucrose octa-esters are unsatisfactory surfactants, and octa-esters are therefore not prepared in the process.

Thus, many prior art methods which react triglycerides and polyol are limited to the synthesis of lower esters, and higher polyesters of polyhydroxy compounds, such as sucrose, are not or cannot be obtained.

The use of such catalysts in both steps increases yield loss and increases color formation in the product.